A conventional extension rod assembly is shown in FIGS. 1 to 3, and generally includes a body 1′ having a sleeve 2′ mounted thereto which is rotatable about the axis of the body 1′ to control a rod 3′ within the body 1′. The body 1′ includes an axial passage 10′ in which the rod 3′ is received, a positioning hole 11′, a radial groove 12′ and a radial restriction hole 13′, wherein the axial passage 10′ communicates with the groove 12′ and the restriction hole 13′. The rod 3′ includes a through hole 30′ which is located corresponding to the groove 12′, and a guide recess 31′ which is located corresponding to the restriction hole 13′. A pin 40′ is inserted into a limitation hole 23′ of the sleeve 2′, the groove 12′ of the body 1′ and the through hole 30′ of the rod 3′. A bead 41′ is located in the restriction hole 13′ of the body 1′ and received in the guide recess 31′ of the rod 3′. A spring 15′ and a ball 16′ are received in the positioning hole 11′ of the body 1′, the ball 16′ is pushed by the spring 15′ and contacts one of two index holes 20′, 21′ of the sleeve 2′ so as to position the sleeve 2′. When rotating the sleeve 2′ about the axis of the body 1′, the pin 40′ is moved within the groove 12′ and the ball 16′ is pushed inward by the sleeve 2′ to compress the spring 15′ as shown in FIG. 2 and the rod 3′ is rotated by the pin 40′. The ball 16′ is engaged with the other index hole 21′ to position the sleeve 2′ at the second position. In the meanwhile, the guide recess 31′ of the rod 3′ is rotated such that the bead 41′ is completely accommodated in the guide recess 31′ and does not protrude from the surface of the body 1′ via the restriction hole 13′ as shown in FIG. 3. In this status, a socket (not shown) can be easily mounted to the body 1′ or removed from the body 1′ because the bead 41′ is merged into the restriction hole 13′. On the contrary, when the sleeve 2′ is rotated to its first position where the bead 41′ partially protrudes out from the rod 3′ via the restriction hole 13′ and contacts against the inner periphery of the socket to position the socket.
However, the body 1′ and the sleeve 2′ each have many positions to be machined to have holes and grooves, and this means a high manufacturing cost is involved. In addition, there are many parts involved which require significant assembling time.
The present invention intends to provide an extension rod assembly with a release device which includes less number of parts and can be manufactured at low cost.